Time-of-flight mass spectrometers comprise an ion source, a pulsed acceleration region, a field free region and a detector. A sample is introduced into the ion source that ionises it, allowing it to be accelerated by a pulsed electric field within the acceleration region. The accelerated ions travel through the field free region at a velocity proportional to the square root of their mass-to-charge ratio. Thus, the time at which the ions arrive at the detector is dependent on their mass-to-charge ratio. Due to practical limitations restricting the length of the field free region, to obtain good mass resolution requires that the detector signal is digitised by an acquisition system sampling in the GHz range.
The output signal is split temporally into two periods; the first defined as the scan time is when the detector signal represents the mass spectrum of the sample, starting from the time when the acceleration pulse occurs. The second time period that is used to separate one scan from another is defined as the inter-scan period.
Even though the sampled signal is processed within an acquisition module to detect peaks, there is still a large amount of data that must be transferred from the acquisition module to the mass spectrometer's embedded computer system and on to its host computer system.
The embedded computer system uses the acquired data on a scan-by-scan basis which requires that the data is transferred in-between two consecutive scans, i.e. in the inter-scan period. During this period the instrument is not acquiring data so this is effectively “dead time”. For this reason, the inter-scan period must be kept to a minimum and hence the data must be transferred as quickly as possible.
As new analysis techniques are developed such as Ion Mobility Spectrometry (IMS), the amount of data per scan increases, requiring ever faster transfer rates.
An object of the present invention is to improve the rate of data throughput in a mass spectrometer data, acquisition system.